Virtually all buildings and structural enclosures where human activity takes place require venting. The type of venting device employed to provide the required venting will depend on the kind of enclosure to be vented and the use to which the vented space is put. For example, bathrooms containing showers typically have active vents with fans to vent moist air and steam to the outdoors. Kitchens, particularly in restaurants and hotels, similarly have powered vents for removing cooking by-products such as smoke and steam to the outdoors.
Other types of enclosures, such as attics, may not require active venting. However, such enclosures do typically require a passive venting device to allow for air flow from the enclosure, through an opening, to the outdoors. Such venting is required, for example, to prevent a buildup of moisture in the enclosure. Rather than forcing air out of the enclosure, passive venting devices typically include a vent structure in the form of upstanding walls defining an aperture to allow airflow between the enclosure and the outdoors. Passive venting devices can also include a screen to block animals, insects and other unwanted objects from entering the enclosed space through the opening in the building enclosure.
Passive venting devices are well-known and have been extensively used in the past. Notably, many jurisdictions have building codes that require passive venting devices for venting attic spaces. House attics and other similar enclosures are sometimes vented simply by one or more passive venting devices on the roof. The passive venting devices are each positioned above a ventilation passage or opening in the roof which permits air to flow from the enclosure to the outside, and vice versa.
Most roof vents are typically constructed for a given predetermined roof slope (or pitch) and area. Accordingly, roof vent suppliers are required to maintain a relatively large inventory of vents in order to accommodate the full range of roof slopes or pitches which are encountered in the building industry. Consequently, roof vent suppliers are faced with the problem of high costs and high storage space if they want to be able to supply roof vents accommodating the full range of roof slopes and venting requirements encountered in the industry.
Accordingly, there exists a need for an adjustable roof vent. The prior art has recognized the need for adjustability of roof vents, as evidenced by several patents disclosing different types of adjustable structures.
For example, U.S. Pat. No. 6,932,690 to Ramsay discloses an adjustable roof ventilator jack for operationally coupling a roof ventilator to a venting aperture extending through a sloped roof. The jack includes a base section having base section front, rear and side walls. The base section is configured so as to be angled in a direction opposite the slope of the roof. The jack also includes a pivotable section having pivotable section front and side walls. The pivotable section front wall is pivotally attached to the base section for pivotal movement between an extended configuration wherein the pivotable and base section front walls are in a substantially parallel relationship relative to each other and a retracted configuration wherein the inner surface of the pivotable and base section front walls form an obtuse angle. The jack further includes a position lock for selectively locking the base and pivotable sections in a predetermined angular relationship relative to each other.
U.S. Pat. No. 2,274,403 to Filkins discloses a chimney, ventilator, or exhaust head for a slope or ridge installation adapted to fit any pitch or slope of roof. The chimney includes an upwardly projecting flange at each side with a central projection for seating a bearing member at opposite sides of a cover-plate. The cover-plate has a skirt which may be uniform on both sides of its center mounting, and preferably two adjusting bolts are provided for holding the cover member in place.
Other prior art patents of general interest in the field of passive venting devices include: U.S. Pat. No. 1,588,321 to Lord, U.S. Pat. No. 2,695,554 to Jenson, U.S. Pat. No. 2,763,196 to Singleton, U.S. Pat. No. 2,890,642 to Fernsten, U.S. Pat. No. 2,909,113 to Hatcher, U.S. Pat. No. 3,075,450 to Noll, U.S. Pat. No. 3,082,677 to Pease, U.S. Pat. No. 3,886,852 to Acosta, U.S. Pat. No. 5,409,266 to Baker, U.S. Pat. No. 5,655,964 to Rheault, and U.S. Pat. No. 7,232,370 to Newell.
However, there is a continuing need for improvement in this area. For example, many of the adjustable passive venting devices, including both the Ramsay roof jack and ventilator combination, and the Filkins chimney are somewhat difficult to adjust in the field. Other drawbacks of the prior art passive venting devices include a) being made from several cooperating parts which makes them costly to manufacture, b) being designed with a reduced net free area flow area through the vent, and c) being provided with a clumsy adjusting mechanism which presents an unclean look and provides gaps for insects and debris to accumulate. Additionally, the Ramsay roof jack/ventilator combination and the Filkins chimney are difficult to handle, heavy, and have the potential for leaks through the sheet metal seams.